An electronic system may be placed into a sleep mode to reduce power consumption. During the sleep mode, a portion of the circuits in the electronic system may have a clock signal turned off or operated at a reduced frequency, have a voltage of a power supply voltage removed or reduced, or both.
The electronic system may be configured to wake from the sleep mode at a programmed time. Wakeup circuits that wake the electronic system may be designed for low power operation. However, the wakeup circuits may not keep time accurately, or may keep time accurately but require additional components that increase the cost of the electronic system.